m1 = 2500; m2 = 320; k1 = 80000; k2 = 500000; b1 = 350; b2 = 15020;
A = [
    0, 0, 1, 0;
    0, 0, 0, 1;
    -k1 / m1, k1 / m1, -b1 / m1, b1 / m1;
    k1 / m2, -(k1 + k2) / m2, b1 / m2, -(b1 + b2) / m2;
    ];
B = [0; b2/m2; (b1*b2) /( m1*m2); (m2*k2-b1*b2-b2^2) / m2^2];
C = [1 -1 0 0];
D = 0;
sys = ss(A, B, C, D);
t=0:0.01:50;
y=step(0.1*sys,t);
plot(t,y)
grid
title('open-loop response to 0.1 m step disturbance (state space)')